JPH0363067B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer composition for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, and the like. [Prior art and problems] As a conventional electrophotographic method, US Patent No. 2297691
No. 2,357,809, etc., electrical conduction is achieved by uniformly charging a photoconductive insulating layer, then exposing the layer to light, and dissipating the charge on the exposed portions. A latent image is formed, and then a colored, electrically charged fine powder called toner is attached to the latent image to make it visible (development process), and the resulting visible image is transferred onto transfer paper, etc. After being transferred onto a material (transfer step), the image is permanently fixed by heating, pressure or other suitable fixing method (fixing step). As described above, the toner must have the functions required not only in the development process but also in each of the transfer and fixing processes. Generally, toner is subjected to mechanical frictional force due to shearing force and impact force during mechanical operation in a developing device, and deteriorates while copying several thousand to tens of thousands of sheets.
To prevent such toner deterioration, it is best to use strong resins with large molecular weights that can withstand mechanical friction forces, but these resins generally have a high softening point and are suitable for open fixing, which is a non-contact fixing method, and infrared rays. With radiant fixing, the thermal efficiency is poor, so fixing is not sufficient.Also, since the contact fixing method has good thermal efficiency, even in the widely used heat roller fixing method, it is necessary to use a heat roller to achieve sufficient fixing. It becomes necessary to raise the temperature of the toner, which not only causes problems such as deterioration of the fixing device, curling of paper, and increased energy consumption, but also has poor pulverization properties when using such resins, so when manufacturing toner, Manufacturing efficiency is significantly reduced. Therefore, it is not possible to use a binder resin whose polymerization degree and even softening point are too high. On the other hand, in the heat roller fixing method, the heating roller surface and the toner image surface of the sheet to be fixed are in pressure contact, so the thermal efficiency is extremely high and it is widely used from low speeds to high speeds. When doing so, a so-called offset phenomenon is likely to occur, in which toner adheres to the surface of the heating roller and is transferred to subsequent transfer paper or the like. In order to prevent this phenomenon, the surface of the heating roller is treated with a material with excellent mold release properties such as a fluorine-based resin, and in addition, a mold release agent such as silicone oil is coated on the surface of the heating roller. However, the method of applying silicone oil or the like is not preferable because the fixing device becomes large and not only expensive but also complicated, which tends to cause trouble. In addition, as described in Japanese Patent Publication No. 55-6895 and Japanese Patent Application Laid-open No. 56-98202, there is a method to improve the offset phenomenon by widening the molecular weight distribution width of the binder resin, but in general, the degree of polymerization of the resin is It becomes necessary to set the fixing temperature higher. As a further improved method, Special Publication No. 57-493,
As described in JP-A-50-44836 and JP-A-57-37353, there is a method of improving the offset phenomenon by making the resin asymmetrical and crosslinking, but the fixing point has not been improved. Generally, the minimum fusing temperature is between low temperature offset and high temperature offset, so the usable temperature range is
The temperature is between the minimum fixing temperature and the high temperature offset, and by lowering the minimum fixing temperature as much as possible and raising the high temperature offset generation temperature as much as possible, the usable fixing temperature can be lowered and the usable temperature range can be expanded, resulting in energy savings. Fast fixing and can prevent paper from curling. In addition, since double-sided copying can be performed without trouble, copying machines are becoming more intelligent, and the temperature control of the fixing device is more accurate.
There are many advantages such as relaxing the tolerance range. Therefore, resins and toners with good fixing properties and offset resistance are always desired. When using a styrene-based binder resin to meet such requirements, a paraffin binder resin is used as described in JP-A-49-65232, JP-A-50-28840, and JP-A-50-81342. A known method is to add oxtail, low molecular weight polyolefin, etc. as an offset preventive agent, but it has been confirmed that if the amount added is small, it is ineffective, and if the amount is too large, the developer deteriorates quickly. Polyester resin inherently has good fixing properties, and as described in U.S. Pat. No. 3,590,000, it can be fixed sufficiently even in a non-contact fixing method, but it is prone to offset phenomenon and cannot be used in a heat roller fixing method. was difficult. As described in JP-A-50-44836, JP-A-57-37353, and JP-A-57-109875, polyester resins with improved offset resistance using polyhydric carboxylic acids have sufficient properties for use. Problems have arisen in that either they do not have offset resistance, or those that do do so at the expense of the low-temperature fixing properties that polyester resins inherently possess. On the other hand, toners using polyester resin may have poor fluidity compared to styrene-based toners.
As a result of the agglomeration, the toner transportability within the developing device deteriorates, and developability deteriorates, resulting in the formation of visible images with poor image quality, such as image unevenness and background smearing. In order to improve the fluidity of toner, a large amount of fluidity improver such as hydrophobic silica fine powder is added, but as a result, surface cleaning of the electrostatic image support is difficult with a urethane rubber blade or the like. If this is done by using a developing device, toner particles may become caught between the blade and the electrostatic image support, resulting in poor cleaning and staining of the visible image. When using an image forming apparatus that has a recycling system that returns the toner to reuse, hydrophobic silica particles are embedded in the surface of the toner particles, reducing the fluidity of the toner and resulting in visible images with poor image quality. Sometimes it was formed. Further, the polyester resin itself has appropriate triboelectric charging properties, and therefore it is possible to impart charging ability to the toner without adding a charge control agent. However, since the resin as a whole is charged, its frictional charging properties gradually increase.For example, as more than 50,000 copies are made in succession, the amount of charge on the toner using polyester resin changes, causing the image This may have a negative effect on visible images, such as a decrease in density. The present invention was made to meet these demands, and its purpose is to provide a developer that can prevent offset without applying an anti-offset liquid in a heat roller fixing system and that can fix at a lower fixing temperature. It is about providing. Another object of the present invention is to provide a developer that has good fluidity, does not cause blocking, and has a long life (hard to deteriorate). A further object of the present invention is to provide a resin and a toner with good pulverizability. [Means for Solving the Problems] That is, the present invention provides that the main component of the binder resin is (a) represented by the following general formula: (In the formula, R is ethylene or propylene group, x,
Each y is an integer greater than or equal to 1, and x+y
The average value of is 2-7. ) a diol component represented by (b) a divalent carboxylic acid or its acid anhydride or its lower alkyl ester; (c) a trihydric or higher polyhydric alcohol; and (d) a trivalent or higher polyhydric carbon. A polyester resin obtained by cocondensation polymerization with an acid, its acid anhydride, or its lower alkyl ester, and the acid value of the polyester resin is AV and the hydroxyl value is OHV.
The present invention relates to an electrophotographic developer composition, which is made of a polyester resin having an OHV/AV value of 1.2 or more, and contains at least two types of charge control agents. In the present invention, in particular, the softening point of the binder resin is 106
-160°C, and the glass transition temperature is preferably 50 to 80°C, and the charge control agent includes at least one positively chargeable charge control agent and at least one negatively chargeable charge control agent. Further, it is preferable that the amount of the positively chargeable charge control agent used is 1/2 or less of the amount of the negatively chargeable charge control agent used. On the other hand, unless a transesterification reaction or a reaction with a monovalent carboxylic acid and/or alcohol is performed, carboxyl groups and/or hydroxyl groups remain at the molecular ends of polyester, but the friction of the polyester resin itself depends on the amount of these end groups. It has been confirmed that the amount of charge changes. If the amount of terminal groups, especially the acid value, is reduced too much, the amount of triboelectricity of the polyester resin will decrease, and if the amount of endgroups, especially the acid value, is increased too much, the amount of triboelectricity of the polyester resin will increase to a certain level, but on the other hand, The environmental dependence after forming into a toner becomes significant, making it difficult to use it as a developer composition. Polyester resins having an acid value of 5 to 60 (KOHmg/g) are often used for toners. Now, when the acid value of polyester resin is AV and the hydroxyl value is OHV, the value of OHV/AV is
Toners made of polyester resins with a viscosity of 1.2 or higher have better fluidity, although the reason for this has not been strictly elucidated, and by using such toners, it has become possible to lower the minimum fixing temperature. The polyester resin used as the main component of the binder resin in the present invention is obtained by condensation polymerization of alcohol and carboxylic acid, carboxylic acid ester, or carboxylic acid anhydride. is polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (3.3)-2,2-bis(4-hydroxyphenyl)
Propane, polyoxyethylene (2.0)-2,2-
Bis(4-hydroxyphenyl)propane, polyoxypropylene (2.0)-polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)
Examples include propane, polyoxypropylene(6)-2,2-bis(4-hydroxyphenyl)propane, and the like. Also, if necessary, other diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol,
1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,
6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol,
Diols such as polytetramethylene glycol,
Bisphenol A, hydrogenated bisphenol A,
10% of other dihydric alcohols in alcohol ingredients
It can be added in an amount of about mol% or less. In addition, the carboxylic acid component (b) in the present invention includes, for example, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, and sebaconic acid. acids, azelaic acid, malonic acid, or alkenylsuccinic acids or alkylsuccinic acids such as n-dodecenylsuccinic acid, n-dodecylsuccinic acid, anhydrides, lower alkyl esters, and other divalent carboxylic acids of these acids. I can do it. Furthermore, the trivalent or higher polyfunctional monomers (c) and (d) in the present invention are preferable components for improving offset development, but if they are too small, the effect is weak, and when they are too large, it is difficult to control the reaction. Not only is it difficult to obtain a polyester resin with stable performance, but also undesirable phenomena occur, such as an increase in the minimum fixing temperature after toner formation. Furthermore, in the past, polyester resins had strong intermolecular forces, making the resin hard and difficult to crush. However, by using a trivalent or higher carboxylic acid component and a trivalent or higher alcohol component together as a crosslinking agent, the resin The crushability of the powder was improved. Although the exact reason is unknown, it is thought that the reduction in the molecular weight between the crosslinking points improves the crushability. However, if too many polyvalent monomer components are used, grindability will deteriorate, so it is desirable that the polyvalent monomers (3) and (2) be combined in an amount of 5 to 60 mol% of the total monomers. . The trivalent or higher polyhydric alcohol component (c) in the present invention includes sorbitol, 1,2,3,6-
Hexanetetrol, 1,4-sorbitane, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2
-Methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane,
Examples include 1,3,5-trihydroxymethylbenzene and other trihydric or higher polyhydric alcohols. In addition, as the (d) trivalent or higher polycarboxylic acid component in the present invention, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid ,
1,2,4-naphthalenetricarboxylic acid, 1,
2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl) methane,
1,2,7,8-octane tetracarboxylic acid, pyromellitic acid, Empol trimer acid, anhydrides and lower alkyl esters of these acids, and as a component that lowers the minimum fixing temperature, the following formula (In the formula, The above carboxylic acids can be mentioned. Examples of the tetracarboxylic acids represented by the above formula include those shown in the following (1) to (12). (1) 4-Neopentylidenyl-1 ,2,6,7-
Heptanetetracarboxylic acid (2) 4-Neopentyl-1,2,6,7-heptene (4)-tetracarboxylic acid (3) 3-Methyl-4-heptenyl-1,2,5,
6-hexanetetracarboxylic acid (4) 3-methyl-3-heptyl-5-methyl-
1,2,6,7-heptene(4)-tetracarboxylic acid(5) 3-nonyl-4-methylidenyl-1,2,
5,6-hexanetetracarboxylic acid (6) 3-decylidenyl-1,2,5,6-hexanetetracarboxylic acid (7) 3-nonyl-1,2,6,7-heptene (4)-
Tetracarboxylic acid (8) 3-decenyl-1,2,5,6-hexanetetracarboxylic acid (9) 3-butyl-3-ethylenyl-1,2,5,
6-hexanetetracarboxylic acid (10) 3-methyl-4-butylidenyl-1,2,
6,7-heptanetetracarboxylic acid (11) 3-methyl-4-butyl-1,2,6,7-
Heptene(4)-tetracarboxylic acid(12) 3-methyl-5-octyl-1,2,6,7
-Heptene(4)-tetracarboxylic acid The binder resin containing polyester resin as the main component used in the present invention has a softening point of 106 to 160°C and a glass transition temperature of 50 to 80°C. However, if the softening point is less than 106°C, it will not be effective in obtaining a sufficient non-offset region, and if the softening point is less than 160°C.
If it exceeds this, undesirable phenomena such as an increase in the minimum fixing temperature will occur. On the other hand, the glass transition temperature
If it is less than 50°C, the storage stability after forming a toner will deteriorate, and if it exceeds 80°C, it will have an adverse effect on fixing properties, which is not preferable. In addition, the acid value and hydroxyl value of polyester resin are JIS
Measured by the method specified in K 0070,
When the ethyl acetate insoluble content is 3% by weight or more, dioxane is preferably used as the acid value measurement solvent. In the present invention, the above acid group is AV, and the hydroxyl value is
When expressed as OHV, the main component of the binder resin is polyester resin with an OHV/AV value of 1.2 or more.
Toner obtained using a polyester resin with an OHV/AV value of less than 1.2 has a higher minimum fixing temperature than a toner obtained using a polyester resin with an OHV/AV value of 1.2 or more, and has poor fluidity. In order to obtain this, it is necessary to add a large amount of a fluidity improver such as hydrophobic silica fine powder, and in this case, as mentioned above, visible images with poor image quality are often formed. Polyester resins with an OHV/AV value of 1.2 or more as described above undergo the polycondensation reaction described above, and it is necessary to take into account the flow of raw monomers out of the reaction system due to monomer evaporation, sublimation, etc. Basically, it can be easily obtained by using a larger number of functional groups in the alcohol component as a whole than in the carboxylic acid component as a whole. The developer composition of the present invention contains the above-mentioned polyester resin and at least two kinds of charge control agents, preferably one or more of each of positively chargeable and negatively chargeable charge control agents, and uses a positively chargeable charge control agent. By reducing the amount to 1/2 or less of the amount of negatively chargeable charge control agent used, it is possible to obtain good visible images without loss of density even if more than 50,000 copies are made continuously. It became. Specific examples of positively chargeable charge control agents include nigrosine dyes, such as "Nigrosine Base EX";
"Oil Black BS", "Oil Black SO",
Triphenylmethane dyes containing tertiary amine as a side chain, such as "Bontron N-01" and "Bontron N-11" (manufactured by Orient Chemical Co., Ltd.), quaternary ammonium salt compounds, such as "Bontron P-
51 (manufactured by Orient Chemical Co., Ltd.), cetyltrimethylammonium bromide, etc., polyamine resins such as "AFP-B" (manufactured by Orient Chemical Co., Ltd.), and others. Specific examples of negatively chargeable charge control agents include metal-containing azo dyes, such as "Varifast Black".
3804", "Bontron S-31", "Bontron S-
32", "Bontron S-34", "Bontron S-36"
(manufactured by Orient Chemical Co., Ltd.), "Eisenspiron Black TVH" (manufactured by Hodogaya Chemical Co., Ltd.), copper phthalocyanine dyes, metal complexes of alkyl derivatives of salicylic acid, such as "Bontron E-82", "Bontron E-84" , "Bontron E-85" (the above,
(manufactured by Orient Chemical Co., Ltd.), and others. The above charge control agent is 0.1~
It is contained in an amount of 8.0% by weight, preferably 0.2 to 5.0% by weight. The polyester resin used in the present invention can be produced by condensation polymerization of a polyhydric carboxylic acid component and a polyol component, for example, at a temperature of 180 to 250°C in an inert gas atmosphere. At this time, an esterification catalyst, which is usually used to accelerate the reaction,
For example, zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, etc. can be used. It can also be produced under reduced pressure for the same purpose. A toner is obtained using the polyester resin according to the present invention as the main component of a binder resin, but for example, in order to improve the crushability in forming a toner, the number average molecular weight
Other resins, such as styrene or styrene-acrylic resins having a molecular weight of 11,000 or less, may be used up to 30% by weight of the binder resin. At the time of toner preparation, in addition to colorants and magnetic substances, property improvers such as wax as an offset prevention agent and hydrophobic silica as a fluidity improver are added, but the polyester resin according to the present invention is used as a binder resin. When used, it is not necessary to add the property improver, and even if it is added, the amount added can be small. Coloring agents used in the present invention include various carbon blacks manufactured by thermal black method, acetylene black method, channel black method, lamp black method, etc., phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green. B,
Examples include Rhodamine-B base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, and mixtures thereof, and are usually used in an amount of about 1 to 15 parts by weight per 100 parts by weight of the binder resin. . In the present invention, the above polyester resin and at least two types of charge control agents are used as essential components,
After uniformly dispersing the colorant and optionally a property improver, a toner with an average particle size of 5 to 15 μm is obtained by melting, kneading, cooling, pulverizing, and classifying using known methods. Powder, i.e. iron oxide carrier;
It can be used as a dry two-component developer by mixing it with a true spherical iron oxide carrier, a ferrite carrier, etc., or a carrier coated with a resin or the like. When making a magnetic toner using the binder resin according to the present invention, the magnetic material is a powder of a ferromagnetic metal such as iron, cobalt, or nickel, or an alloy or compound containing a ferromagnetic element such as ferrite, hematite, or magnetite. The magnetic material is in the form of a fine powder with an average particle size of 0.1 to 1 μm and is mixed with a binder resin of 100 μm.
It can be used by dispersing about 40 to 70 parts by weight. [Examples] Hereinafter, examples of manufacturing a binder resin and examples of the present invention will be described, but the present invention is not limited to these examples. It should be noted that all composition ratios shown in Examples are expressed in parts by weight. Production example 1 Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane 500g, polyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane 371g, trimethylolpropane 38g of succinic acid, 258g of succinic acid, and 1,2,4
-Pour 88 g of benzenetricarboxylic acid into a 4-necked glass flask, attach a thermometer, stainless steel stirring rod, falling condenser, and nitrogen inlet tube, and heat in a mantle heater under a nitrogen stream.
The reaction was carried out at 200°C with stirring. The degree of polymerization is
Tracking was performed from the softening point according to ASTM E28-51T, and the reaction was terminated when the softening point reached 122°C.
The obtained resin was a pale yellow solid, and the glass transition temperature measured by DSC (differential calorimeter) was 65°C.
In addition, the acid value of the resin is 16KOHmg/g, and the hydroxyl value is
It was 30KOHmg/g. Binding resin (1)
shall be. Production Example 2 Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane 900g, trimethylolethane 34g, isooctenylsuccinic acid
102 g, azelaic acid 169 g, 1,2,4-benzenetricarboxylic acid 126 g, and 3-methyl-4-
The same apparatus as in Production Example 1 using 109 g of heptenyl-1,2,5,6-hexanetetracarboxylic acid,
Depending on the procedure, the softening point is 122℃, the glass transition temperature is 60℃,
A polyester resin having an acid value of 15 KOH mg/g and a hydroxyl value of 30 KOH mg/g was obtained. This resin is referred to as a binder resin (2). Production Example 3 Same as Production Example (1) using 1050 g of polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, 339 g of azelaic acid, and 141 g of 1,2,4-benzenetricarboxylic acid. The softening point is 122℃ and the glass transition temperature is
60℃, acid value 19KOHmg/g, hydroxyl value 31KOHmg/
g of polyester resin was obtained. This resin is referred to as a binder resin (3). Production example 4 Polyoxypropylene (2.2)-2,2-(4-
The same apparatus and procedure as in Production Example 1 were carried out using 578 g of hydroxyphenyl)propane, 176 g of polyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane, 72 g of trimethylolpropane, and 473 g of isophthalic acid. As a result, a polyester resin having a softening point of 122° C., a glass transition temperature of 63° C., an acid group of 23 KOH mg/g, and a hydroxyl value of 32 KOH mg/g was obtained. This resin is referred to as a binder resin (4). Production Example 5 In the same manner as Production Example 1 except that the amount of succinic acid was changed to 290g, the softening point was 122℃, the glass transition temperature was 64℃, the acid value was 26KOHmg/g, and the hydroxyl value was
A polyester resin containing 22 KOHmg/g was obtained. This resin is referred to as a binder resin (5). Production Example 6 In Production Example 1, the reaction was completed when the softening point reached 105℃, the glass transition temperature was 62℃, and the acid value was 62℃.
A polyester resin having a hydroxyl value of 18 KOH mg/g and a hydroxyl value of 36 KOH mg/g was obtained. This resin is referred to as a binder resin (6). Regarding the binder resins obtained in Production Examples 1 to 6 above, the crushability of the resins was simply evaluated by the following method. The results are shown in Table 1. <Simple crushing test> The resin that has undergone the normal crushing process is passed through a sieve, and
Obtain resin powder that passes through the mesh but does not pass through 20 meshes. 30.00 of the above classified resin powder
g Precise weighing, coffee mill (PHLIPS HR-
2170 type) for 15 seconds, pass through a 32-mesh sieve, and accurately weigh the weight (A) of the resin that does not pass through.
The residual rate is determined by the following formula: Residual rate (%) = A (g) / Weight of resin before coffee mill grinding (30.00 g) x 100. The above operation is performed three times and averaged, and the average residual rate is 0 to 100. 15.0%〔◎〕, 15.1
~30.0% [〇], 30.1~45.0% [△], 45.1~
Display 100% as [×]. Examples 1 to 3, Comparative Examples 1 to 7 Materials having the following compositions were mixed in a ball mill, then melted and kneaded in a pressure kneader, cooled, and then subjected to normal pulverization and classification processes to prepare toner with an average particle size of 11 μm. . <Composition> Example 1 Binder resin (1) 90 parts carbon black "Regal 400R" (manufactured by Cabot Corporation) 7 parts negatively chargeable charge control agent "Eisenspiron Black TVH" (manufactured by Hodogaya Chemical Co., Ltd.) 2 parts positively charged 0.9 parts of negative charge control agent "Bontron P-51" (manufactured by Orient Chemical Co., Ltd.) Example 2 Binder resin (2) 90 parts of carbon black "Regal 400R" 7 parts of negative charge control agent "Bontron S-34" (manufactured by Orient Chemical Co., Ltd.) (manufactured by Orient Chemical Co., Ltd.) 2 parts Positive charge control agent "Bontron N-01" (manufactured by Orient Chemical Co., Ltd.) 0.9 parts Example 3 Binder resin (1) 90 parts Carbon Black "Regal 400R" 7 parts Negative charge control agent Control agent “Bontron E-84” (manufactured by Orient Chemical Co., Ltd.) Two-part positively chargeable charge control agent “Bontron N-11” (manufactured by Orient Chemical Co., Ltd.) 0.9 parts Comparative example 1 Binder resin (1) 90 parts Carbon black “ "Regal 400R" 7 parts Comparative example 2 Binder resin (1) 90 parts Carbon black "Regal 400R" 7 parts Negative charge control agent "Eisenspiron Black TVH" 2 parts Comparative example 3 Binder resin (1) 90 parts Carbon black “Regal 400R” 7-part positive charge control agent “Bontron P-51”
0.9 parts Comparative example 4 Binder resin (3) 90 parts Carbon Black "Regal 400R" 7 parts Negative charge control agent "Eisenspiron Black TVH" 2 parts Positive charge control agent "Bontron P-51"
0.9 parts Comparative example 5 Binder resin (4) 90 parts Carbon Black "Regal 400R" 7 parts Negative charge control agent "Eisenspiron Black TVH" 2 parts Positive charge control agent "Bontron P-51"
0.9 parts Comparative example 6 Binder resin (5) 90 parts Carbon Black "Regal 400R" 7 parts Negative charge control agent "Eisenspiron Black TVH" 2 parts Positive charge control agent "Bontron P-51"
0.9 parts Comparative example 7 Binder resin (6) 90 parts Carbon Black "Regal 400R" 7 parts Negative charge control agent "Eisenspiron Black TVH" 2 parts Positive charge control agent "Bontron P-51"
0.9 part The toners obtained in Examples 1 to 3 above are referred to as Toner 1 to Toner 3, respectively, and the toners obtained in Comparative Examples 1 to 7 are referred to as Comparative Toner 1 to Comparative Toner 7, respectively. 39g each of the above toners and resin-coated iron powder
A commercially available electrophotographic copying machine (the photoreceptor is amorphous selenium, the rotation speed of the fixing roller is 255 mm/sec, the temperature of the heat roller in the fixing device is variable, and the oil coating device is Images were taken with The fixing temperature was controlled between 120°C and 220°C, and the image fixing and offset properties were evaluated. Table 1 shows the results.
Shown below. The minimum fixing temperature here is 15mm x 7.5mm on the bottom.
A load of 500 g was placed on a sand eraser, and the image fixed through the fixing machine was rubbed back and forth 5 times. The optical reflection density was measured using a Macbeth reflection densitometer before and after rubbing, and the fixing rate was determined by the following definition. This refers to the temperature of the fixing roller when it exceeds 70%. Fixation rate = Image density after rubbing / Image density before rubbing However, comparative toner 6 has poor toner fluidity.
The toner transport performance within the developing device is poor, and as a result,
Image unevenness and background stains appeared from the initial image. Comparative Toner 7 had a low minimum fixing temperature, but a narrow non-offset area. For comparative toners 1 and 2, the image density began to decrease when the number of continuous copies exceeded 53,000 sheets, and the image density remained low even after 70,000 sheets were printed. Comparative toner 3 caused background smearing from the beginning. Regarding comparative toners 4 and 5, the fixing properties were also
The toner conveyance was good, and the image quality was good from the initial stage up to 120,000 sheets, but not only the binder resin used for comparison toners 4 and 5 but also the toner had poor crushability. It was. On the other hand, Toners 1 to 3 of the present invention had good fixing properties, good pulverization properties, and good toner transport properties, and the visible image quality was good from the initial stage up to 120,000 sheets. 【table】

Claims (1)

[Claims] 1. The main component of the binder resin is (a) represented by the following formula: (In the formula, R is ethylene or propylene group, x,
Each y is an integer greater than or equal to 1, and x+y
The average value of is 2-7. ) a diol component represented by (b) a divalent carboxylic acid or its acid anhydride or its lower alkyl ester; (c) a trihydric or higher polyhydric alcohol; and (d) a trivalent or higher polyhydric carbon. An acid or its acid anhydride or its lower alkyl ester is cocondensed in an amount such that the polyvalent monomer components (c) and (d) above account for a total of 5 to 60% of the total monomers. It is a polyester resin, and the acid value of the polyester resin is
When AV and hydroxyl value are OHV, OHV/
It is made of a polyester resin having an AV value of 1.2 or more, the softening point of the binder resin is 106 to 160°C, the glass transition temperature is 50 to 80°C, and at least two types of charge control agents. , the charge control agent comprises at least one positively chargeable charge control agent and at least one negatively chargeable charge control agent; The amount used is 1/2 of the amount of negatively chargeable charge control agent used.
An electrophotographic developer composition characterized by the following: